This invention relates generally to a method for electronically controlling an input clutch of a manual transmission on the basis of direct, real-time driveline measurements inside the transmission or in a vehicle driveline.
The market share of vehicles equipped with manual transmissions remains low in this country partly due to operating complexity involved in the gear shifting process. A typical manual transmission system requires a coordinated use of feet to operate the transmission input clutch and throttle pedals while moving a shift fork through a hand-operated shift lever. It also requires a foot-based control to slip the clutch for driving a vehicle at a low speed.
Missed clutch release timing, poor clutch slip control or missed engagement timing results in a stalled engine or undesirable noise, vibration and harshness (NVH) such as clutch shudder.
A robotized manual transmission system with electronically-controlled input clutch has been in use for limited production applications. Its clutch control primarily relies on clutch actuator position and slip speed measurements at the sliding clutch plates during clutch release, slip and engagement processes. However, these measurements cannot be directly utilized to accurately compute torque transmitted through the slipping input clutch, so the system is not reacting directly to a measure of clutch torque. Consequently, such a system cannot reliably take corrective closed-loop actions in real time. More specifically, there is no reliable method to accurately estimate clutch torque based on clutch actuator position and slip speed across sliding clutch plates under all drive conditions because of limited understanding of dry clutch friction mechanisms. Accordingly, a conventional controller of the robotized manual transmission system is not well suited to detect undesirable NVH behaviors and take corrective closed-loop actions in real-time during clutch release, slip and engagement processes.